LPC2921 datasheet(19/83 Pages) NXP

19 / 83 page

LPC2921_23_25_1

Preliminary data sheet

Rev. 01 — 15 June 2009

19 of 83

NXP Semiconductors

LPC2921/2923/2925

ARM9 microcontroller with CAN, LIN, and USB

The index sector is a special sector in which the JTAG access protection and sector

security are located. The address space becomes visible by setting the FS_ISS bit and

overlaps the regular ﬂash sector’s address space.

Note that the index sector, once programmed, cannot be erased. Any ﬂash operation must

be executed out of SRAM (internal or external).

6.8.3 Flash bridge wait-states

To eliminate the delay associated with synchronizing ﬂash-read data, a predeﬁned

number of wait-states must be programmed. These depend on ﬂash-memory response

time and system clock period. The minimum wait-states value can be calculated with the

following formulas:

Synchronous reading:

(1)

Asynchronous reading:

(2)

Remark: If the programmed number of wait-states is more than three, ﬂash-data reading

cannot be performed at full speed (i.e. with zero wait-states at the AHB bus) if speculative

reading is active.

6.8.4 Pin description

The ﬂash memory controller has no external pins. However, the ﬂash can be programmed

via the JTAG pins, see Section 6.6.3.

6.8.5 Clock description

The ﬂash memory controller is clocked by CLK_SYS_FMC, see Section 6.7.2.

0x2000 A000

yes

0x2000 C000

yes

0x2000 E000

yes

0x2001 0000

yes

0x2002 0000

yes

0x2003 0000

yes

0x2004 0000

yes

0x2005 0000

yes

0x2006 0000

yes

0x2007 0000

yes

Table 10.

Flash sector overview …continued

Flash memory

sector number

Sector size (kB)

Flash memory

address

LPC2921

LPC2923

LPC2925

WST

acc clk

()

tclk sys

()

------------------

–

WST

acc addr

()

tclk sys

()

----------------------

–

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